The present invention relates to structural and informational articles that readily disperse (lose mechanical integrity and preferably dissolve) upon contact with aqueous base.
Many articles in everyday use cause unwanted bulk in landfills due to their inability to biodegrade, e.g. polystyrene cups. A variety of current so-called biodegradable materials actually do not degrade in landfills due to the lack of oxygen and moisture reaching such materials as they become buried ever deeper in the landfills. Even some materials that can be recycled (e.g. polyethylene terephthalate or PET bottles) cannot be economically recycled due to the inability to remove the paper labels from the bottles. Additional packaging items that cause disposal problems include body-waste bags which can be used to store specimen samples or are used for receipt of body wastes. Even though the contents of the bags may be biodegradable, the packaging is not.
One proposal for making disposable articles is to coat a water soluble polymer with a degradable polymer such as poly(3-hydroxybutyrate) (U.S. Pats. Nos. 4,372,311 and 4,620,999). Other approaches include laminating biodegradable barrier films to non-biodegradable materials (U.S. Pats. Nos. 3,661,695, 3,934,587, and 3,952,347).
Ideally, the packaging or informational item (e.g. a label) possesses the requisite properties to withstand its intended use, such as a hot cup for retaining hot coffee, hot tea, hot chocolate, or the like; yet which under specified conditions can be readily dispersed for disposal and/or recovery and recycle of the materials. For present purposes, a "dispersible" article is one which can be dissolved or otherwise sufficiently solvated in either 14% NH.sub.4 OH or a 5% Alconox solution so that it loses its mechanical integrity and is in a form that can be safely disposed and/or subjected to recovery procedures.